In conventional communication systems, an electronic circuit is used to demodulate an amplitude or frequency modulated wireless signal.
For example, a multi-mode wireless transmission system disclosed in Korean Patent Application No. 10-1999-0007404 can perform multi-mode wireless communication in such a manner that functions common to respective communication methods are shared as common modulation and demodulation functions and functions different between the respective communication methods are provided as different modulation and demodulation functions by forming electronic circuits separately provided for the respective communication methods.
Furthermore, a wireless communication system and a wireless digital receiver for use in the system disclosed in Korean Patent Application No. 10-2006-7000266 can perform wireless communication using different demodulation digital circuits in such a manner that an electronic circuit for down-converting a signal into a low-frequency signal, oversampling the signal and demodulating the wireless signal is formed at a base station and an electronic circuit for down-converting a signal into a low-frequency signal, undersampling the signal, and demodulating the wireless signal is formed at a mobile station.
FIG. 1 is a diagram illustrating the configuration of a conventional electronic circuit ASK wireless receiver.
Referring to FIG. 1, a conventional direct conversion-type wireless communication device fabricated based on electronic circuits includes a VCO 40, a PLL frequency locking circuit 50, an RF switch 10, a mixer 20, and a band filter 30. Accordingly, the conventional technology is problematic in that products thereof have a large size and high power consumption, and is also problematic in that the parts thereof are expensive and high-speed communication is limited because the conventional technology is based on a low-speed communication method operating in a narrow band that is achieved by the additional use of a filter.